NMR studies of two types are to be performed on open chain neuroactive and chemotactic peptides. The first is to continue to develop methods which allow an accurate derivation of the manifold of interconverting conformations of peptides in solution from experimental spectral density and coupling constant information. The second is to study rates of interconversion of conformations in these peptides by rotating frame NMR spin-lattice relaxation experiments. Emphasis is on peptides whose cell receptor systems may be defined at the molecular level.